1. Field of the Invention
The present invention relates to a piezoelectric body and a liquid discharge head.
2. Description of the Related Art
A research has been conducted in which a ferroelectric material or dielectric material is formed into a thin film to be used as a piezoelectric body for MEMS (Micro ElectroMechanical Systems) or the like. In particular, a research has been actively conducted in which an ABO3 perovskite type oxide is formed into a film to be made into a piezoelectric body, wherein an attempt to enhance a property of the element through the control of the crystalline orientation of the perovskite oxide has been made.
For example, Japanese Patent Application Laid-Open No. H06-350154 discloses a piezoelectric body having a rhombohedral or tetragonal PZT film made of lead zirconate titanium (sometimes referred to as PZT) having a composition within a composition range that is normally tetragonal in a bulk. The piezoelectric body described above is characterized in that the <111> orientation in the case of the rhombohedral PZT film and the <001> orientation in the case of the tetragonal PZT film are 70% or higher with respect to the direction vertical to the major surface of the substrate. However, since these materials include Pb as an A-site atom, the effect to the environment is a problem.
Therefore, there has been proposed a piezoelectric body using BiFeO3 perovskite oxide (e.g., see Japanese Patent Application Laid-Open No. 2005-39166). The BiFeO3 compound disclosed in Japanese Patent Application Laid-Open No. 2005-39166 is also disclosed in “Science”, Mar. 14, 2003, vol. 299, No. 5613, p. 1719, as a material having a large remanent polarization. However, there is no description about a piezoelectric body whose B-site atom is an atom of an element other than Fe.
Considering that PbTiO3 having large remanent polarization is not preferably used as a piezoelectric material, it is considered that a high-performance characteristic could not be provided only by BiFeO3. Actually, the invention of Japanese Patent Application Laid-Open No. 2005-39166 describes that an atom of an element such as Mn, Ru, Co, Ni, V, Nb, Ta, W, Ti, Zr, Hf, etc. is added as a B-site atom. However, since the utilized crystal structure is made only of a tetragonal structure or rhombohedral structure, a displacement characteristic or optical characteristic is not utilized in the area where the piezoelectric characteristic is enhanced.
Further, as for Mn, Ru, Co, and Ni disclosed as a magnetic metal element added to BiFeO3, the effect of enhancing magnetism cannot be expected as the addition effect within the range where the additive exceeds 10% with respect to all B-sites in the crystal structure constituting the piezoelectric film.